Layout data saving method, layout data converting device and graphic verifying device

ABSTRACT

There are saved layout data which have parent cell information indicative of higher order cell data to directly refer to low order cell data (or basic element data), thereby defining a reverse hierarchical structure. More specifically, both of basic element data (figD 1  and figD 2 ) have cell data (cell 2 ) as the parent cell information, all of basic element data (figD 3  to figD 5 ) have cell data (cell 3 ) as the parent cell information, the cell data (cell 3 ) have two identical cell data (cell 2  and cell 2 ) as the parent cell information, and the cell data (cell 2 ) have three identical cell data (cell 3 , cell 3  and cell 3 ) as the parent cell information.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of saving layout datacomprising a plurality of basic element data, each of which directlydefines a graphic to be a layout pattern of a component of asemiconductor device and a plurality of cell data constructed by ahierarchical structure which can finally refer to the basic elementdata.

2. Description of the Background Art

Conventionally, data (layout data) having a layout of a circuit patternof a large scale integrated circuit (LSI) has been saved in the formconforming to a GDS2STREAM format released from CALMA Co., Ltd. TheGDS2STREAM format currently spreads widely in the world and has actuallybecome a standard format. In a general applying method, therefore, dataare converted into the GDS2STREAM format and are thus transferred to asoftware manufactured by other companies if necessary.

In the GDS2STREAM format, first of all, a top cell of the highest orderhierarchy to be a starting point is specified and graphic data andanother cell to which reference is to be made are specified in the topcell. Graphic data and another cell to which reference is to be made arealso specified in a cell to which reference has been made. The referencerelationship is recursively repeated until a cell (graphic data) in thelowest layer is reached. Accordingly, all data can be processedsequentially by following the hierarchical structure of the cell fromthe top cell of the highest hierarchy in order. Thus, the GDS2STREAMformat has a feature that a whole file is constituted by describing thehierarchical structure.

FIG. 18 is a diagram showing an example in which layout data are savedaccording to the conventional art. FIG. 19 is a diagram showing a treestructure of the layout data saved in the format illustrated in FIG. 18.

As shown in these drawings, the data present a hierarchical structure.FIG. 18 shows the following description by three cell data cell1 tocell3.

cell1{cell2, cell2, cell2}

cell2{figD1, figD2, cell3, cell3}

cell3{figD3, figD4, figD5}

It is assumed that figD1 to figD5 are graphic data. The graphic data arealso referred to as “basic element data” and actually imply data on onesquare or one rectangle. For example, an oblong rectangle, a thinvertical rectangle and a small square are piled up so that a transistorcan be formed. For respective attributes, the oblong rectangle acts asan active region, the thin vertical rectangle acts as a gate and thesmall square acts as a contact hole for a source, a gate and a drain.Thus, the basic element data (graphic data) define a graphic to be alayout pattern of a component of a semiconductor device.

In the cell data cell1 of the highest order hierarchy according to theexample, reference is made to the lower order cell data cell2 threetimes. Therefore, the figD1 and figD2 included in the cell2 are usedthree times. For the cell2, furthermore, reference is made to the lowerorder cell data cell3 twice. Therefore, the figD3 to figD5 included inthe cell3 are used as the cell1 six times. If the data of the cell1 areexpanded flatly (into only graphic data), the following flat data can beobtained.

{figD1, figD2, figD3, figD4, figD5, figD3, figD4, figD5, figD1, figD2,figD3, figD4, figD5, figD3, figD4, figD5, figD1, figD2, figD3, figD4,figD5, figD3, figD4, figD5}

Thus, the same graphic data are repetitively described many times. TheGDS2STREAM format utilizes the hierarchical structure and therefore hasa more compact data structure correspondingly as compared with theexample of the flat expansion. This tendency is more remarkable when thesame format is used as layout data of an LSI handling large scale data.

Thus, the data format having the hierarchical structure is veryefficient because it simply changes the contents of reference of a cellwhen a work for repetitively using a certain basic graphic or moving andcopying a comparatively large data volume is often generated.

In layout data using an ordinary hierarchical structure represented bythe GDS2STREAM format, a low order cell and graphic data to whichreference is made (which will be hereinafter referred to as a “childcell”) are specified in a cell as described above. To the contrary,however, a high order cell to which reference is made (which will behereinafter referred to as a “parent cell”) is not specified in thecell. More specifically, cell data from a high order to a low order arespecified to implement the hierarchical structure.

In order to check a range in which higher order cells are influencedwhen an inner part of a certain cell is corrected, therefore, it isnecessary to expand and check data by reversely following all thehierarchical structures one by one. For the use in which a mutualpositional relationship between graphics included in separate cells istaken into consideration, moreover, it is necessary to once expand ahierarchical structure to form a flat data structure. For this reason, aprocessing efficiency is reduced as compared with that in flat dataoriginally having no hierarchical structure. The layout data volume ofan LSI becomes enormous. Therefore, there is a problem in that acapacity of a storage device such as a disk or a memory is exceeded anda normal processing cannot be carried out when the hierarchicalstructure is to be expanded to generate flat data.

In order to eliminate such a drawback, it is necessary to have specialknow-how, for example, to take note of the reference relationshipbetween cells in a layout data design stage or to take care that thecells do not overlap with adjacent cells.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method of savinglayout data having a structure in which an influence exerted wholly by achange in a graphic and the like defined by basic element data can bechecked comparatively easily.

A first aspect of the present invention is directed to a method ofsaving layout data including a plurality of basic element data, each ofwhich directly defines a graphic to be a layout pattern of a componentof a semiconductor device and a plurality of cell data constructed by ahierarchical structure such that reference can be finally made to thebasic element data. In the layout data saving method, the layout data issaved in such a format as to define the hierarchical structure in areverse direction from a low order to a high order by relating to parentcell information indicative of high order cell data to which referenceis directly made to each of the plurality of basic element data and theplurality of cell data.

The layout data saving method serves to define and save the hierarchicalstructure in the reverse direction defining a hierarchical relationshipfrom a low order to a high order. By sequentially retrieving the celldata in a higher order hierarchy with the parent cell information of thebasic element data set to be a starting point, consequently, it ispossible to comparatively easily check an influence exerted wholly by achange in a graphic and the like defined by the basic element data.

A second aspect of the present invention is directed to a layout dataconverting device for converting first type layout data into second typelayout data. The first type and second type layout data have a pluralityof basic element data, each of which directly defines a graphic to be alayout pattern of a component of a semiconductor device and a pluralityof cell data constructed by a hierarchical structure such that referencecan be finally made to the basic element data, respectively. Each of theplurality of the cell data in the first type layout data have child cellinformation indicative of low order cell data or the basic element datato which reference is directly made, thereby defining the hierarchicalstructure in a positive direction. Each of the plurality of the basicelement data and the plurality of cell data in the second type layoutdata have parent cell information indicative of high order cell data towhich reference is directly made, thereby defining the hierarchicalstructure in a reverse direction. The layout data converting deviceincludes a hierarchical structure analyzing section and a reversehierarchical structure generating section. The hierarchical structureanalyzing section analyzes the hierarchical structure based on the childcell information of the first type layout data. The reverse hierarchicalstructure generating section adds the parent cell information to each ofthe plurality of basic element data and the plurality of cell datarespectively to generate the second type layout data based on a resultof analysis carried out by the hierarchical structure analyzing section.

The layout data converting device can convert the first type layout datainto the second type layout data. Therefore, it is possible toeffectively utilize the existing first type layout data as the secondtype layout data.

A third aspect of the present invention is directed to a layout dataconverting device for converting second type layout data into first typelayout data. The first type and second type layout data have a pluralityof basic element data, each of which directly defines a graphic to be alayout pattern of a component of a semiconductor device and a pluralityof cell data constructed by a hierarchical structure such that referencecan be finally made to the basic element data. Each of the plurality ofthe cell data in the first type layout data have child cell informationindicative of low order cell data or the basic element data to whichreference is directly made, thereby defining the hierarchical structurein a positive direction. Each of the plurality of the basic element dataand the plurality of cell data in the second type layout data haveparent cell information indicative of high order cell data to whichreference is directly made, thereby defining the hierarchical structurein a reverse direction. The layout data converting device includes areverse hierarchical structure analyzing section and a hierarchicalstructure generating section. The reverse hierarchical structureanalyzing section analyzes the hierarchical structure based on theparent cell information of the second type layout data. The hierarchicalstructure generating section adds the child cell information to each ofthe plurality of cell data respectively to generate the first typelayout data based on a result of analysis carried out by the reversehierarchical structure analyzing section.

The layout data converting device can convert the second type layoutdata into the first type layout data. Therefore, it is possible toobtain a compatibility of the existing first type layout data and thesecond type layout data defining the hierarchical structure in thereverse direction.

A fourth aspect of the present invention is directed to a graphicverifying device for carrying out a graphic verification processingbased on layout data. The layout data have a plurality of basic elementdata, each of which directly defines a graphic to be a layout pattern ofa component of a semiconductor device and a plurality of cell dataconstructed by a hierarchical structure such that reference can befinally made to the basic element data. Each of the plurality of basicelement data and the plurality of cell data have parent cell informationto be information about high order cell data to which reference isdirectly made, thereby defining the hierarchical structure in a reversedirection. The graphic verifying device includes a reverse hierarchicalstructure analyzing section and a graphic verifying section. The reversehierarchical structure analyzing section analyzes the hierarchicalstructure based on the parent cell information of the layout data. Thegraphic verifying section carries out a verification processing based onan occupied region on an actual space region of a graphic defined by theplurality of basic element data on the basis of a result of analysisperformed by the hierarchical structure analyzing section.

The graphic verifying device can comparatively easily recognize theoccupied region on the actual space region of the graphic defined by thebasic element data by sequentially retrieving the high order cell datawith the parent cell information of the basic element data set to be astarting point. Thus, a graphic can be verified efficiently.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a method of saving layout data according toa first embodiment of the present invention,

FIG. 2 is a flow chart showing a method of generating layout data havinga reverse hierarchical structure,

FIG. 3 is a diagram showing a layout data saving state according to thefirst embodiment,

FIG. 4 is a diagram showing, in a tree format, the layout data savingstate according to the first embodiment,

FIG. 5 is a diagram illustrating a hierarchical structure in layoutdata,

FIG. 6 is a block diagram showing a structure of a layout dataconverting device according to a second embodiment of the presentinvention,

FIG. 7 is a flow chart showing an operation of the layout dataconverting device according to the second embodiment,

FIG. 8 is a block diagram showing a structure of a layout dataconverting device according to a third embodiment of the presentinvention,

FIG. 9 is a flow chart showing an operation of the layout dataconverting device according to the third embodiment,

FIG. 10 is a block diagram showing a structure of an occupation rateanalyzing device according to a fourth embodiment of the presentinvention,

FIG. 11 is a flow chart showing an occupation rate calculating operationof the occupation rate analyzing device according to the fourthembodiment,

FIG. 12 is a block diagram showing a structure of an occupation rateanalyzing device according to a fifth embodiment of the presentinvention,

FIG. 13 is a flow chart showing an occupation rate calculating operationof the occupation rate analyzing device according to the fifthembodiment,

FIG. 14 is a block diagram showing a structure of a Fourier analyzingdevice according to a sixth embodiment of the present invention,

FIG. 15 is a flow chart showing a Fourier analyzing operation of theFourier analyzing device according to the sixth embodiment,

FIG. 16 is a block diagram showing a structure of a Fourier analyzingdevice according to a seventh embodiment of the present invention,

FIG. 17 is a flow chart showing a Fourier analyzing operation of theFourier analyzing device according to the seventh embodiment,

FIG. 18 is a diagram showing a layout data saving state according to theconventional art, and

FIG. 19 is a diagram showing, in a tree format, the layout data savingstate according to the conventional art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

<First Embodiment>

FIG. 1 is a diagram showing a layout data saving format according to afirst embodiment of the present invention. An arrow in FIG. 1 indicatesa reference direction. As shown in FIG. 1, there is presented ahierarchical structure from a low order to a high order in order of abasic element data describing section 11, a cell data describing section12, a cell data describing section 13 and a highest order cell datadescribing section 14.

Reference is directly made to the basic element data describing section11 from the cell data describing section 12, the cell data describingsection 13 or the highest order cell data describing section 14, and thebasic element data describing section 11 has parent cell information(corresponding to the arrow in FIG. 1) indicative of high order celldata to which reference is directly made.

Reference is directly made to the cell data describing section 12 fromthe cell data describing section 13 or the highest order cell datadescribing section 14, and the cell data describing section 12 hasparent cell information indicative of high order cell data to whichreference is directly made.

Reference is directly made to the cell data describing section 13 fromanother cell data describing section 13 or the highest order cell datadescribing section 14, and the cell data describing section 13 hasparent cell information indicative of high order cell data to whichreference is directly made.

The highest order cell data describing section 14 does not have theparent cell information because of the highest hierarchy.

In the layout data saving format according to the first embodiment,thus, saving is carried out with a reverse hierarchical structure inwhich a hierarchical relationship is clear from a low order to a highorder in a reverse direction to that in the conventional art. In thisspecification, a direction from the high order to the low order and adirection from the low order to the high order in the hierarchicalstructure will be hereinafter referred to as positive and reversedirections, respectively.

FIG. 2 is a flow chart showing a method of generating layout data havingthe reverse hierarchical structure. With reference to FIG. 2,description will be given to an operation for generating a layout datastructure according to the first embodiment.

At a step S11, basic element data DP are created. The basic element dataDP are graphic data and have parent cell information indicative of highorder cell data to which reference is directly made in order to satisfythe reverse hierarchical structure in addition to information and anattribute which indicate a graphic itself in the same manner as in theconventional art. The basic element data DP correspond to the basicelement data describing section 11.

At a step S12, first level cell data CL1 to refer to the basic elementdata DP are described. The first level cell data CL1 do not includechild cell information indicative of a hierarchical relationship withthe basic element data DP to which reference is to be made, and insteadinclude parent cell information indicative of high order cell data towhich reference is directly made.

Examples of the first level cell data CL1 include cells having a basiclogical function such as AND, OR, NOT and NAND with reference to one ormore basic element data DP.

At a step S13, second level cell data CL2 to refer to the first levelcell data CL1 are described. The second level cell data CL2 do notinclude child cell information indicative of a hierarchical relationshipwith the first level cell data CL1 to which reference is to be made butinclude parent cell information indicative of high order cell data towhich reference is directly made. There is a possibility that othersecond level cell data CL2 might refer to the second level cell dataCL2. Therefore, an operation for describing the second level cell dataCL2 by the cell data describing section 13 is executed recursively.

Examples of the second level cell data CL2 include a cell to be acommand having a higher function in combination with the first levelcell data CL1 and the basic element data DP. Moreover, the second levelcell data CL2 may partially refer to the basic element data DP.

At a step S14, finally, the highest level cell data CLX to which anycell does not refer are described. In some cases, the first level celldata CL1 and the second level cell data CL2 act as the highest levelcell data CLX.

The basic element data DP, the first level cell data CL1, the secondlevel cell data CL2 and the highest level cell data CLX have regioninformation for defining sizes, origin positions and the like on spacesprescribed by themselves.

Thus, the layout data to be saved in the layout data saving formataccording to the first embodiment present the reverse hierarchicalstructure in which cell data have parent cell information.

FIG. 3 is a diagram showing the layout data saving state according tothe first embodiment. FIG. 4 is a diagram showing a tree structure oflayout data saved in the format illustrated in FIG. 3. The layout datashown in FIGS. 3 and 4 correspond to layout data shown in FIGS. 18 and19.

As shown in FIGS. 3 and 4, cell data (including basic element data) haveparent cell information indicative of high order cell data to whichreference is to be directly made. More specifically, both of basicelement data figD1 and figD2 have cell data cell2 as parent cellinformation, all of basic element data figD3 to figD5 have cell datacell3 as the parent cell information, the cell data cell3 have twoidentical cell data cell2 and cell2 as the parent cell information, andthe cell data cell2 have three identical cell data cell1, cell1 and cellas the parent cell information.

Accordingly, it is apparent that the figD4 can efficiently andaccurately recognize a relationship with all the cell data to whichreference is to be made (the cell3 (to which reference is once made),the cell2 (to which reference is made twice through the cell3) and thecell1 (to which reference is made six times through the cell2 and thecell3)) by setting the parent cell information (cell3) of the figD4 tobe a starting point.

In the case in which a graphic of the basic element data DP iscorrected, the correction reaches all the cells which refer to the basicelement data DP directly or indirectly. In a conventional method ofsaving layout data having a hierarchical structure, only a hierarchicalrelationship in the positive direction is defined. Therefore, it is hardto correctly grasp an influence exerted wholly by the correction of thebasic element data DP in the lowest level.

In the layout data saving format according to the first embodiment,however, the hierarchical relationship is defined in a reversedirection. Therefore, the retrieval is carried out by setting the parentcell information of the basic element data DP as a starting point.Consequently, it is possible to efficiently and accurately recognize theinfluence exerted wholly by the correction of the basic element data DP.

FIG. 5 is a diagram illustrating the hierarchical structure in thelayout data. In the example of FIG. 5, a semiconductor chip 1 to be thehighest order cell data is provided with a memory 2, an input/outputinterface 3 and a logic circuit 4 to be lower order cell data thereof.Furthermore, the memory 2 is provided with a peripheral circuit 5 and amemory cell array 6 to be lower order cell data thereof, and a largenumber of memory cells 7 to be lower order cell data are provided in amatrix on the memory cell array 6. The memory cell 7 is provided withbasic elements F0, F1 and F2 to be graphics defined by basic elementdata positioned in the lowest order of the hierarchical structure.

For example, in the case in which the basic element data F2 are changed,an influence exerted on the semiconductor chip 1 through the memory cellarray 6 (all the memory cells 7) and the memory 2 can be recognizedcomparatively easily by following the parent cell information with theparent cell information of the basic element data F2 set to be astarting point in the layout data having the reverse hierarchicalstructure according to the first embodiment.

<Second Embodiment>

FIG. 6 is a block diagram showing a structure of a layout dataconverting device according to a second embodiment of the presentinvention.

As shown in FIG. 6, a hierarchical structure analyzing section 21analyzes a hierarchical structure based on hierarchical structure layoutdata DH and outputs hierarchical structure analyzing information D21. Areverse hierarchical structure generating section 22 outputs reversehierarchical structure layout data RDH based on the hierarchicalstructure analyzing information D21.

FIG. 7 is a flow chart showing an operation of the layout dataconverting device according to the second embodiment. With reference toFIG. 7, the converting operation will be described below. First of all,description will be given to a hierarchical structure analyzingoperation to be carried out by the hierarchical structure analyzingsection 21.

First of all, the highest order cell data are retrieved from thehierarchical structure layout data DH at a step S21 and low order celldata are retrieved from child cell information of the highest order celldata at a step S22.

Then, lower order hierarchical data are retrieved from the child cellinformation of the low order cell data detected at the step S22. In thecase in which the low order cell data thus retrieved further have celldata as child cell information, a processing of a step S23 is executedrecursively.

Thereafter, basic element data are retrieved as the lowest order celldata at a step S24. Under certain circumstances, the basic element dataare retrieved after the execution of the steps S21 and S22.

After the steps S21 to S24, the hierarchical structure analyzing section21 obtains the hierarchical structure analyzing information D21including a hierarchical relationship (a parent—child relationship) ofall the basic element data and cell data and inherent information in thecell data.

Next, there is started an operation for generating the reversehierarchical structure layout data RDH based on the hierarchicalstructure analyzing information D21 which is to be carried out by thereverse hierarchical structure generating section 22.

At a step S25, basic element data are created. Inherent information suchas information about graphic data in the basic element data is the sameas that of the hierarchical structure layout data DH. By newly addingparent cell information indicative of high order cell data to whichreference is directly made, basic element data having a reversehierarchical structure are created.

Then, cell data to refer to the basic element data are created at a stepS26. In this case, the cell data do not have child cell informationindicative of a hierarchical relationship with the basic element dataand parent cell information indicative of high order cell data to whichreference is directly made is added.

At a step S27, next, cell data to refer to the cell data are created. Inthis case, the generated cell data do not have the child cellinformation indicative of the hierarchical relationship with the celldata to which reference is to be made and parent cell informationindicative of high order cell data to which reference is directly madeis added. In the case in which other cell data further refer to thegenerated cell data, the processing of the step S27 is executedrecursively.

Then, the highest order cell data are generated at a step S28. Thehighest order cell data do not have the child cell information.

Thus, the layout data converting device according to the secondembodiment can convert the hierarchical structure layout data DH intothe reverse hierarchical structure layout data RDH. Therefore, it ispossible to practically use existing hierarchical structure layout dataas reverse hierarchical structure layout data.

A large number of existing designed layout data are saved as thehierarchical structure layout data based on a GDS2STREAM format. By thelayout data converting device according to the second embodiment,therefore, it is possible to maintain a compatibility with the existinghierarchical structure layout data. If the compatibility can bemaintained, it is also possible to properly use a conventionalhierarchical structure and the reverse hierarchical structure accordingto the present invention if necessary.

<Third Embodiment>

FIG. 8 is a block diagram showing a structure of a layout dataconverting device according to a third embodiment of the presentinvention.

As shown in FIG. 8, a reverse hierarchical structure analyzing section31 analyzes a reverse hierarchical structure based on reversehierarchical structure layout data RDH and outputs reverse hierarchicalstructure analyzing information D31. A hierarchical structure generatingsection 32 outputs hierarchical structure layout data DH based on thereverse hierarchical structure analyzing information D31.

FIG. 9 is a flow chart showing an operation of the layout dataconverting device according to the third embodiment. With reference toFIG. 9, the converting operation will be described below. First of all,description will be given to a reverse hierarchical structure analyzingoperation to be carried out by the reverse hierarchical structureanalyzing section 31.

First of all, basic element data are retrieved from the reversehierarchical structure layout data RDH at a step S31 and cell data torefer to the basic element data are retrieved from parent cellinformation of the basic element data at a step S32.

Then, higher order cell data are retrieved from the parent cellinformation of the cell data detected at the step S32. In the case inwhich the higher order cell data thus retrieved further have cell dataas parent cell information, a processing of a step S33 is executedrecursively.

Thereafter, the highest order cell data are retrieved by following theparent cell information of the cell data at a step S34. Under certaincircumstances, the highest order cell data are retrieved after theexecution of the steps S31 and S32.

After the steps S31 to S34, the reverse hierarchical structure analyzingsection 31 obtains the reverse hierarchical structure analyzinginformation D31 including a hierarchical relationship (a parent—childrelationship) of all the cell data and inherent information in the celldata.

Next, there is started an operation for generating the hierarchicalstructure layout data DH based on the reverse hierarchical structureanalyzing information D31 which is to be carried out by the hierarchicalstructure generating section 32.

At a step S35, the highest order cell data are created. In this case,child cell information is added, thereby creating the highest order celldata based on an existing hierarchical structure.

Then, low order cell data are created by referring to the child cellinformation of the highest order cell at a step S36. In this case, thechild cell information to be information about the cell data to whichreference is to be made is added to the cell data.

Next, lower order cell data are created by referring to the child cellinformation of the cell data at a step S37. In this case, child cellinformation indicative of cell data to which reference is to be made isadded. In the case in which child cell information of the generated celldata has other cell data, the processing of the step S37 is executedrecursively.

Then, basic element data are generated at a step S38.

Thus, the layout data converting device according to the thirdembodiment can convert the reverse hierarchical structure layout dataRDH into the hierarchical structure layout data DH. Therefore, it ispossible to maintain a compatibility with existing hierarchicalstructure layout data. If the compatibility can be maintained, it isalso possible to properly use a conventional hierarchical structure andthe reverse hierarchical structure according to the present invention ifnecessary.

<Fourth Embodiment>

FIG. 10 is a block diagram showing a structure of an occupation rateanalyzing device according to a fourth embodiment of the presentinvention. As shown in FIG. 10, a reverse hierarchical structureanalyzing section 41 receives reverse hierarchical structure layout dataRDH and outputs reverse hierarchical structure analyzing information D41based on the reverse hierarchical structure layout data RDH. Anoccupation rate calculating section 42 to be a graphic verifying sectionoutputs an occupation rate calculation result D42 based on the reversehierarchical structure analyzing information D41.

The occupation rate analyzing device may employ a structure in which thereverse hierarchical structure layout data RDH are directly used or astructure in which the reverse hierarchical structure layout data RDHobtained by converting existing hierarchical structure layout data DH bymeans of a reciprocal hierarchical data converting section 20 are usedas shown in FIG. 10. The layout data converting device according to thesecond embodiment corresponds to the reciprocal hierarchical dataconverting section 20.

FIG. 11 is a flow chart showing an occupation rate calculating operationof the occupation rate analyzing device according to the fourthembodiment. FIG. 11 corresponds to the structure of FIG. 10 in which theexisting hierarchical structure layout data DH are utilized. Withreference to FIG. 11, description will be given to the occupation ratecalculating operation.

First of all, the hierarchical structure layout data DH are convertedinto reverse hierarchical structure layout data RDH by the reciprocalhierarchical data converting section 20 at a step S41.

Subsequently, a reverse hierarchical structure analysis processing basedon the reverse hierarchical structure layout data RDH is carried out bythe reverse hierarchical structure analyzing section 41.

First of all, basic element data are extracted at a step S42.

At a step S43, next, high order cell data are retrieved based on parentcell information of the basic element data.

At a step S44, furthermore, high order cell data are retrieved based onparent cell information of the cell data. If parent cell data of thecell data thus retrieved are present, the processing of the step S44 isexecuted recursively.

At a step S45, then, the highest order cell data are finally retrievedby following the parent cell information. Depending on a structure ofthe reverse hierarchical structure layout data RDH, the step S45 isexecuted immediately after the execution of the steps S42 and S43 insome cases.

When the highest order cell data are retrieved, an actual space regionto be defined by the highest order cell data is determined. A graphicdefined by at least one basic element data is used in the actual spaceregion. Therefore, the actual space region becomes an object of theoccupation rate calculation to be one of graphic verifications.

Subsequently, there is started an occupation rate calculation processingbased on the reverse hierarchical structure analyzing information D41which is to be carried out by the occupation rate calculating section42. In the present embodiment, a processing is executed on a mesh regionunit on the assumption that the actual space region is constituted by aplurality of mesh regions.

First of all, at a step S46, absolute coordinates of a graphic definedby basic element data are calculated. A coordinate position of thegraphic defined by the basic element data on the actual space region isdetermined based on region information about all the cell data from thebasic element data to the highest order cell data.

For instance, in the example of FIG. 5, absolute coordinates on which agraphic defined by basic element data F2 is present are not decideduntil a hierarchical structure comprising a memory cell 7, a memory cellarray 6, a memory 2 and a semiconductor chip 1 becomes clear, and apredetermined position of the predetermined memory cell 7 in the memorycell array 6 of the memory 2 formed on the semiconductor chip 1 is setto be a position in which the basic element data F2 are to be formed.

At a step S47, a region in which a selected mesh region overlaps agraphic having absolute coordinates decided at the step S46 is extractedas an occupied region of a graphic on the mesh region.

At a step S47C, presence (Yes/No) of the extraction of all the basicelement data is checked. If the basic element data are not extracted,the processing returns to the step S42. Subsequently, the processing ofthe steps S42 to S47 is repeated for all the basic element data and adecision of Yes is then obtained at the step S47C, and the processingproceeds to a step S48.

At the step S48, in the case in which two graphics overlap each other onthe same region, an occupied region transformation processing ofremoving an overlapping portion from an occupied region of one of thegraphics is carried out.

At a step S49, next, an occupation rate in the selected mesh region iscalculated based on a total area of the occupied region obtained throughthe steps S47 and S48. In this case, at the step S48, the occupiedregion transformation processing is carried out. Also in the case inwhich two or more graphics occupy the same region, therefore, anoccupied region of each graphic is simply added so that the total areaof the occupied region can be obtained accurately.

Then, presence of an end of the calculation of occupation rates in allthe mesh regions is checked at a step S49C. Moreover, if it is decidedthat there is a mesh region in which the calculation is not ended, a newmesh region is selected at a step S49M and the processing then returnsto the step S42.

Thereafter, when it is decided that the calculation of the occupationrates in all the mesh regions is ended at the step S49C, the calculationof the whole occupation rate is carried out based on the occupation ratein each of all the mesh regions at a step S50 and the processing isended.

In the case in which the occupation rate is to be calculated based onthe existing hierarchical structure layout data DH, it is necessary tocause a hierarchy to sequentially descend from high order cell data, toretrieve basic element data and to then follow the hierarchy to thehighest order, thereby carrying out the same calculation as that in thesteps S42 to S50.

In this case, it is necessary to once expand a hierarchical structureinto flat data. Therefore, a processing time required for the expansionand an intermediate file (a work region) become enormous so that theprocessing cannot be carried out in some cases.

On the other hand, in the present embodiment, the basic element data ofthe reverse hierarchical structure layout data RDH are used. Therefore,the processing is started from the basic element data and high ordercell data are easily followed. Consequently, a processing of retrievingcell data can easily be carried out so that occupation rate calculationcan be performed at a high speed.

In a fourth embodiment, moreover, there is provided the reciprocalhierarchical data converting section 20 for converting the hierarchicalstructure layout data DH into the reverse hierarchical structure layoutdata RDH. Therefore, it is possible to calculate an occupation rate at ahigh speed in the same manner also in the case in which the hierarchicalstructure layout data DH are given.

<Fifth Embodiment>

FIG. 12 is a block diagram showing a structure of an occupation rateanalyzing device according to a fifth embodiment of the presentinvention. As shown in FIG. 12, a reverse hierarchical structureanalyzing section 41 receives reverse hierarchical structure layout dataRDH and outputs reverse hierarchical structure analyzing information D41based on the reverse hierarchical structure layout data RDH. Anoccupation rate calculating section 52 outputs an occupation ratecalculation result D52 based on the reverse hierarchical structureanalyzing information D41.

The occupation rate analyzing device may employ a structure in which thereverse hierarchical structure layout data RDH are directly used or astructure in which the reverse hierarchical structure layout data RDHobtained by converting existing hierarchical structure layout data DH bymeans of a reciprocal hierarchical data converting section 20 are usedas shown in FIG. 12. The layout data converting device according to thesecond embodiment corresponds to the reciprocal hierarchical dataconverting section 20.

FIG. 13 is a flow chart showing an occupation rate calculating operationof the occupation rate analyzing device according to the fifthembodiment. FIG. 13 corresponds to the structure of FIG. 12 utilizingthe existing hierarchical structure layout data DH. With reference toFIG. 13, the occupation rate calculating operation will be describedbelow.

First of all, at a step S51, the hierarchical structure layout data DHare converted into the reverse hierarchical structure layout data RDH bythe reciprocal hierarchical data converting section 20.

Subsequently, the same reverse hierarchical structure analysisprocessing as that of the fourth embodiment is carried out based on thereverse hierarchical structure layout data RDH by the reversehierarchical structure analyzing section 41. More specifically, thecontents of the processing of steps S52 to S55 in FIG. 13 are the sameas those of the steps S42 to S45 in FIG. 11.

When the highest order cell data are retrieved at the step S55, anactual space region to be defined by the highest order cell data isdetermined. A graphic defined by at least one basic element data is usedin the actual space region. Therefore, the actual space region becomesan object of the occupation rate calculation.

Subsequently, there is started an occupation rate calculation processingbased on the reverse hierarchical structure analyzing information D41which is to be carried out by the occupation rate calculating section52.

First of all, at a step S56, absolute coordinates of the basic elementdata are calculated. Absolute coordinate positions of a graphic definedby the basic element data on an actual space region are determined basedon region information about all the cell data from the basic elementdata to the highest order cell data.

At a step S57, a region in which a selected mesh region overlaps agraphic having absolute coordinates decided at the step S56 is extractedas an occupied region of a graphic on the mesh region.

At a step S57C, presence (Yes/No) of the extraction of all the basicelement data is checked. If the basic element data are not extracted,the processing returns to the step S52. Subsequently, the processing ofthe steps S52 to S57 is repeated for all the basic element data and adecision of Yes is then obtained at the step S57C, and the processingproceeds to a step S58.

At the step S58, in the case in which two graphics overlap each other onthe same region, the overlapping portion is generated as a graphic forsubtraction.

At a step S59, next, an area of the graphic for subtraction which isobtained at the step S58 is subtracted from a simple overlapping areaobtained by simply adding the occupied region extracted at the step S57.Consequently, the occupied area in the selected mesh region can becalculated easily and accurately. In this case, individual occupiedregions themselves are not transformed. Therefore, shapes of theindividual occupied regions are not complicated.

Then, presence of an end of the calculation of occupation rates in allthe mesh regions is checked at a step S59C. Moreover, if it is decidedthat there is a mesh region in which the calculation is not ended, a newmesh region is selected at a step S59M and the processing then returnsto the step S52.

Thereafter, when it is decided that the calculation of the occupationrates in all the mesh regions is ended at the step S59C, the calculationof the whole occupation rate is carried out based on the occupation ratein each of all the mesh regions at a step S60 and the processing isended.

In the case in which the occupation rate calculation is carried out bythe existing hierarchical structure layout data DH in the same manner,it is necessary to expand the hierarchical structure into flat data.Therefore, a processing time required for the expansion and anintermediate file (a work region) become enormous and the processingcannot be carried out in some cases.

On the other hand, in the present embodiment, the processing can bestarted from the basic element data of the reverse hierarchicalstructure layout data RDH. Consequently, a processing of retrieving celldata can easily be carried out and the occupation rate calculation canbe performed at a high speed.

In the fifth embodiment, moreover, there is provided the reciprocalhierarchical data converting section 20 for converting the hierarchicalstructure layout data DH into the reverse hierarchical structure layoutdata RDH. Therefore, it is possible to calculate an occupation rate at ahigh speed in the same manner also in the case in which the hierarchicalstructure layout data DH are given.

<Sixth Embodiment>

FIG. 14 is a block diagram showing a structure of a Fourier analyzingdevice according to a sixth embodiment of the present invention. Asshown in FIG. 14, a reverse hierarchical structure analyzing section 41receives reverse hierarchical structure layout data RDH and outputsreverse hierarchical structure analyzing information D41 based on thereverse hierarchical structure layout data RDH. A Fourier analyzingsection 62 to be a graphic verifying section outputs an analysis resultD62 based on the reverse hierarchical structure analyzing informationD41.

The Fourier analyzing device may employ a structure in which the reversehierarchical structure layout data RDH are directly used or a structurein which the reverse hierarchical structure layout data RDH obtained byconverting existing hierarchical structure layout data DH by means of areciprocal hierarchical data converting section 20 are used as shown inFIG. 14. The layout data converting device according to the secondembodiment corresponds to the reciprocal hierarchical data convertingsection 20.

FIG. 15 is a flow chart showing a Fourier analyzing operation of theFourier analyzing device according to the sixth embodiment. FIG. 15corresponds to the structure of FIG. 14 utilizing the existinghierarchical structure layout data DH. With reference to FIG. 15, theFourier analyzing operation will be described below.

First of all, at a step S61, the hierarchical structure layout data DHare converted into the reverse hierarchical structure layout data RDH bythe reciprocal hierarchical data converting section 20.

Subsequently, the same reverse hierarchical structure analysisprocessing as that of the fourth embodiment is carried out based on thereverse hierarchical structure layout data RDH by the reversehierarchical structure analyzing section 41. More specifically, thecontents of the processing of steps S62 to S65 in FIG. 15 are the sameas those of the steps S42 to S45 in FIG. 11.

When the highest order cell data are retrieved at the step S65, anactual space region to be defined by the highest order cell data isdetermined. A graphic defined by at least one basic element data is usedin the actual space region. Therefore, the actual space region becomesan object of the Fourier analysis processing to be one of graphicverifications.

Subsequently, there is started the Fourier analysis processing based onthe reverse hierarchical structure analyzing information D41 by theFourier analyzing section 62.

First of all, at a step S66, absolute coordinates of the basic elementdata are calculated. Coordinate positions of the basic element data onan actual space region are determined based on region information aboutall the cell data from the basic element data to the highest order celldata.

At a step S67, an overlapping region of a selected mesh region in theactual space region and a graphic having coordinate positions decided atthe step S66 is extracted as an occupied region.

At a step S67C, presence (Yes/No) of the extraction of all the basicelement data is checked. If the basic element data are not extracted,the processing returns to the step S62. Subsequently, the processing ofthe steps S62 to S67 is repeated for all the basic element data and adecision of Yes is then obtained at the step S67C, and the processingproceeds to a step S68.

At the step S68, in the case in which two graphics overlap each other onthe same region, an occupied region transformation processing ofremoving the overlapping portion from an occupied region of one of thegraphics is carried out.

At a step S69, then, a Fourier image in the selected mesh region iscalculated based on the occupied region obtained through the steps S67and S68. In this case, the occupied region transformation processing iscarried out at the step S68. Also in the case in which two or moregraphics occupy the same region, therefore, it is possible to accuratelydetermine the occupied region by simply adding the occupied region ofeach graphic.

Thereafter, the Fourier image is subjected to inverse Fouriertransformation at a step S70. Thus, a result of the Fourier analysisprocessing becomes an analysis result D62 on a mesh region unit at thesteps S69 and S70.

Subsequently, presence of an end of the Fourier analysis processing inall the mesh regions is checked at a step S70C. Moreover, if it isdecided that there is a mesh region in which the calculation is notended, a new mesh region is selected at a step S70M and the processingthen returns to the step S62.

Thereafter, when it is decided that the analysis of all the mesh regionsis ended at the step S70C, the processing is completed.

In the case in which the Fourier analysis processing is carried out bythe existing hierarchical structure layout data DH in the same manner,it is necessary to expand the hierarchical structure into flat data.Therefore, a processing time required for the expansion and anintermediate file (a work region) become enormous and the processingcannot be carried out in some cases.

On the other hand, in the present embodiment, the basic element data ofthe reverse hierarchical structure layout data RDH are used.Consequently, the processing of retrieving cell data can easily becarried out and the Fourier analysis can be performed at a high speed.In addition, it is possible to analyze a physical phenomenon at acomparatively long distance by carrying out the Fourier analysis.

In the sixth embodiment, moreover, there is provided the reciprocalhierarchical data converting section 20 for converting the hierarchicalstructure layout data DH into the reverse hierarchical structure layoutdata RDH. Therefore, it is possible to carry out the Fourier analysisprocessing at a high speed in the same manner also in the case in whichthe hierarchical structure layout data DH are given.

<Seventh Embodiment>

FIG. 16 is a block diagram showing a structure of a Fourier analyzingdevice according to a seventh embodiment of the present invention. Asshown in FIG. 16, a reverse hierarchical structure analyzing section 41receives reverse hierarchical structure layout data RDH and outputsreverse hierarchical structure analyzing information D41 based on thereverse hierarchical structure layout data RDH. A Fourier analyzingsection 72 outputs an analysis result D72 based on the reversehierarchical structure analyzing information D41.

The Fourier analyzing device may employ a structure in which the reversehierarchical structure layout data RDH are directly used or a structurein which the reverse hierarchical structure layout data RDH obtained byconverting existing hierarchical structure layout data DH by means of areciprocal hierarchical data converting section 20 are used as shown inFIG. 16. The layout data converting device according to the secondembodiment corresponds to the reciprocal hierarchical data convertingsection 20.

FIG. 17 is a flow chart showing an occupation rate calculating operationof the Fourier analyzing device according to the seventh embodiment.FIG. 17 corresponds to the structure of FIG. 16 utilizing the existinghierarchical structure layout data DH. With reference to FIG. 17, theFourier analyzing operation will be described below.

First of all, at a step S71, the hierarchical structure layout data DHare converted into the reverse hierarchical structure layout data RDH bythe reciprocal hierarchical data converting section 20.

Subsequently, the same reverse hierarchical structure analysisprocessing as that of the fourth embodiment is carried out based on thereverse hierarchical structure layout data RDH by the reversehierarchical structure analyzing section 41. More specifically, thecontents of the processing of steps S72 to S75 in FIG. 17 are the sameas those of the steps S42 to S45 in FIG. 11.

When the highest order cell data are retrieved at the step S75, anactual space region to be defined by the highest order cell data isdetermined. A graphic defined by at least one basic element data is usedin the actual space region. Therefore, the actual space region becomesan object of the Fourier analysis.

Subsequently, there is started the Fourier analysis processing based onthe reverse hierarchical structure analyzing information D41 by theFourier analyzing section 72.

First of all, at a step S76, absolute coordinates of the basic elementdata are calculated. Coordinate positions of the basic element data onan actual space region are determined based on region information aboutall the cell data from the basic element data to the highest order celldata.

At a step S77, an overlapping region of a selected mesh region in theactual space region and a graphic having coordinate positions determinedat the step S76 is extracted as an occupied region.

At a step S77C, presence (Yes/No) of the extraction of all the basicelement data is checked. If the basic element data are not extracted,the processing returns to the step S72. Subsequently, the processing ofthe steps S72 to S77 is repeated for all the basic element data and adecision of Yes is then obtained at the step S77C, and the processingproceeds to a step S78.

At the step S78, in the case in which two graphics overlap each other onthe same region, the overlapping portion is generated as a graphic forsubtraction.

At a step S79, next, an area of the graphic for subtraction which isobtained at the step S78 is subtracted from a simple overlapping areaobtained by simply adding the occupied region extracted at the step S77.Consequently, a total occupied region in the selected mesh region can beobtained easily and accurately and a Fourier image in the total occupiedregion is calculated. In this case, individual occupied regionsthemselves are not transformed. Therefore, shapes of the individualoccupied regions are not complicated.

Thereafter, the Fourier image is subjected to inverse Fouriertransformation at a step S80. A result obtained by the processing of thesteps S78 and S79 becomes an analysis result D72.

Subsequently, presence of an end of the calculation of occupation ratesin all the Fourier mesh regions is checked at a step S80C. Moreover, ifit is decided that there is a mesh region in which the Fourier analysisis not ended, a new mesh region is selected at a step S80M and theprocessing then returns to the step S72.

Then, when it is decided that the analysis of all the mesh regions isended at the step S80C, the processing is completed.

In the case in which the Fourier analysis is to be carried out by theexisting hierarchical structure layout data DH in the same manner, it isnecessary to expand the hierarchical structure into flat data.Therefore, a processing time required for the expansion and anintermediate file (a work region) become enormous and the processingcannot be carried out in some cases.

On the other hand, in the present embodiment, the basic element data ofthe reverse hierarchical structure layout data RDH are used.Consequently, the processing of retrieving cell data can easily becarried out and the Fourier analysis processing can be performed at ahigh speed.

In the seventh embodiment, moreover, there is provided the reciprocalhierarchical data converting section 20 for converting the hierarchicalstructure layout data DH into the reverse hierarchical structure layoutdata RDH. Therefore, it is possible to carry out the Fourier analysisprocessing at a high speed in the same manner also in the case in whichthe hierarchical structure layout data DH are given.

While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore understood that numerous modifications andvariations can be devised without departing from the scope of theinvention.

1. A method of saving layout data comprising a plurality of basicelement data, each of which directly defines a graphic to be a layoutpattern of a component of a semiconductor device and a plurality of celldata constructed by a hierarchical structure such that reference can befinally made to said basic element data, saving said layout data in sucha format as to define said hierarchical structure in a reverse directionfrom a low order to a high order by relating to parent cell informationindicative of high order cell data to which reference is directly madeto each of said plurality of basic element data and said plurality ofcell data, wherein, said plurality of cell data includes intermediatelevel cell data and highest order cell data, and the order of data ofsaid hierarchical structure, from highest to lowest, is said basicelement data, said intermediate level cell data, and said highest ordercell data.